Help pls

[Chaser4837]

A friend of mine has a 200tdi with an incredibly rough idel, spitting tons of black smoke. It drive fine for half the day then whent tits up...

I have a d90 same as him but am unfamiliar with diesel engines (learning as I go)
his is an 85 tdi just looking and comparing there doesn't seam to be anything odviously wrong.
Could it be a head gasket? Any insight at all would be greatly appreciated.
Thank you vary much

[dunerunner]

My guess would be fuel metering to begin with. Electronic fuel injection gone haywire?

[Chaser4837]

How would I go about doing that?

[dunerunner]

What does the exhaust smell like? Diesel, engine oil, coolant? Is the turbo spooling up? I'm just fishing here, as all the diesels I have worked on had mechanical injector pumps and pressure operated injectors.

[Les Parker]

Do you know when the timing belt or timing itself was checked?
Valve clearances?
Does the vehicle accelerate well?
Please supply some further data to go on.

[Chaser4837]

Had a look at it an asked him some questions
It was 'totally rebuilt' 50,000 miles ago.
It was running fine, parked it for a few hours before driving it again and it had trouble starting, then puffed black smoke, acceleratied fine till he tried going up a mountain rd. by then he noticed the idel was extremely lumpy.

[Chaser4837]

When I got there we tried starting it, it didn't want to stay ideling, and was acting as if a cylinder was misfiring ( if that can happen on a diesel)
That was all I had time to do, I'll be headed up his way tomorrow so any suggestions on what to check first would be greatly appreciated.
Again thank you vary much

[Boston]

How about starting with basics. Check fuel line pressure, replace fuel filters etc.

[Maryland 110]

Its a diesel. Start with the fuel filter. Given the rapid onset I'd suspect bad fuel. Black smoke is soot which results from improperly atomized fuel. Many diesel drivers respond "I changed the fuel filter 6 mos ago so that cannot be it", thats crap. Diesels are incredibly sensitive to fuel contamination which happens all the time. A prudent diesel owner carries a spare filter @ all times. When you change the filter be sure to fill it before screwing it on. Fill it with diesel, kerosene, atf, whatever floats your boat. I use atf. I have had the fuel pickup @ the tank fail/develop an air leak and cause symptoms like you describe but doubt thats your issue. Does your friend have any idea when the timing belt was last changed, if it was rebuilt 50k ago its time to change it again. Valves are supposed to be adjusted every 12k. These are incredibly reliable engines but ignoring mandatory service intervals will definately lead to problems.

[Chaser4837]

Changed the filter... Helped but didn't cure.... It has a hard time getting started and running at idel, smothes out when laying on the pedal a tad but when backing off it nearly stalls... Back to head scratching.

[Boston]

Bad fuel water in fuel etc.

[Maryland 110]

Is the lift pump functioning ? Have you used the finger lever with the bleed screw open to see how much fuel the pomp is feeding the injection pump ? If yes, then try running it with the bleed screw loose. Often if there is an air leak before the lift pump the pump pressurizes and air locks the injection pump. If the truck runs better with the bleed screw open (it will leak a bit of fuel but thats ok) then you have an air leak on the suction side of the fuel system.

[Chaser4837]

It's runnin now, but the idel sounds slow and lumpy... If held abut open it all smooths out... Can the idel adjustments loosen up? If adjusted would it only fix a symptom and cover an underlying problem?